CVE-2026-76442

CVE-2026-76442 groups multiple internally discovered vulnerabilities in Cisco Secure Email Gateway (formerly Email Security Appliance) and Cisco Secure Email and Web Manager (formerly Security Management Appliance) that stem from improper validation of a specified quantity in input (CWE-1284 pillar). The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) indicates the flaws are exploitable remotely over the network with no authentication, no user interaction, and low attack complexity, with impact limited to availability. An unauthenticated attacker can send specially crafted input that improperly consumes or crashes the affected service, causing denial of service and disrupting inbound and outbound mail flow for organizations that rely on these gateways. The issues were found during Cisco's proactive internal security review and are addressed in Cisco's software hardening releases. There is no known public proof-of-concept, no evidence of in-the-wild exploitation, and the CVE is not in CISA's KEV catalog.

What to do: Upgrade Cisco Secure Email Gateway and Cisco Secure Email and Web Manager to the latest fixed builds listed in Cisco's PSIRT advisory, since no specific version numbers were provided in the source data. Restrict management and web administration interfaces to trusted internal networks and verify normal SMTP processing and mail queue drainage after patching. Until patched, monitor appliance CPU, memory, and service availability for signs of resource exhaustion or crashes.